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Where are you saving the pictures? SD card or the internal storage?
Unmount it > save the pictures on your internal storage > see if you experience the lag.
Sorry to hear that you have issues with the camera.
To have this fixed i recommend that you contact a repair center. For more information about how to submit your phone for repair and where, contact your local support team.
Scratches are generally not covered by warranty so you may need to pay for having this fixed.